1. Field of the Invention
The present invention relates to a method for producing a 2′-deoxyribonucleosides such as 2′-deoxyguanosine and a microorganism suitably used for the method. 2′-Deoxyribonucleosides are useful as raw materials of drugs, intermediate thereof and so forth.
2. Description of the Related Art
As methods for producing 2′-deoxyribonucleosides, there are known chemical synthesis methods, methods of extracting them from hydrolysates of DNA and biochemical production methods.
As the biochemical methods, there are known methods of producing 2′-deoxyribofuranosylpurine and 2′-deoxyribofuranosylthioguanine (Japanese Patent Laid-open Publication (Kokai) No. 58-63393), 2′-deoxycytidine (Japanese Patent Laid-open Publication No. 01-060396) and 2′-deoxythymidine (Japanese Patent Laid-open Publication No. 01-104190) by using nucleoside phosphorylases of microorganisms.
Further, as methods that utilize microorganisms, there have been disclosed a method of producing 2′-deoxyadenosine from deoxyribose-1-phosphate or a salt thereof and adenine, adenosine or 5′-adenylic acid, a method of producing 2′-deoxyadenosine from 2′-deoxyuridine or thymidine and adenine, adenosine or 5′-adenylic acid in the presence of inorganic phosphoric acid or a salt thereof, a method of producing 2′-deoxyguanosine from 2′-deoxyribose-1-phosphate or a salt thereof and guanine, guanosine or 5′-guanylic acid, and a method of producing 2′-deoxyguanosine from 2′-deoxyuridine or thymidine and guanine, guanosine or 5′-guanylic acid in the presence of inorganic phosphoric acid or a salt thereof (Japanese Patent Laid-open Publication No. 11-137290).
There has also been reported a method of producing a 2′-deoxyribonucleoside-5′-phosphate from a ribonucleotide as a raw material in the presence of a reducing agent such as dithiothreitol by using a recombinant type enzyme, which is obtained by isolating a gene for ribonucleoside triphosphate reductase of a Lactobacillus bacterium and expressing this gene in Escherichia coli (Brunella, A. et al., Journal of Molecular Catalysis B: Enzymatic, 10, 215–222 (2000)).
Furthermore, there have been reported a method of producing thymine or thymidine by culture utilizing viable microbial cells (Japanese Patent Laid-open Publication No. 2-39894).